1. Field of the Invention
The present invention relates to a digital television (IV) broadcast signal receiver that can receive digital television broadcast signals such as ATSC (Advanced television systems Committee).
2. Description of the Related Art
In the North American Continent where an ATSC digital television broadcast (it is abbreviated to a hereinafter TV broadcast) is performed, plains are dotted with metropolises, so that various TV broadcast signals broadcasted in the suburbs of each metropolis can be received at other cities or the halfway point of the cities. In consideration from a user who receives the TV broadcast signals, since many TV broadcast signals are transmitted in various directions, it is necessary to regulate a direction of an antenna in an orientation to a TV broadcasting station from which a program which he wants to watch is delivered. Therefore, a multi-directional antenna such as a smart antenna is put into practical use.
According to the EIA-909 technical standard, it is provided that a smart antenna has sixteen signal receiving directions in respective directions where a circle is divided into sixteen. A digital TV broadcast signal receiver in compliance with the EIA-909 technical standard can switch an effective signal receiving direction of the multi-directional antenna such as the smart antenna to one of all the sixteen signal receiving directions.
Among such digital TV broadcast signal receivers, there is a product having an automatic scanning function for selecting a signal receiving direction of a multi-directional antenna at which a digital TV broadcast signal of a channel chosen by a user in a most suitable condition. In the digital TV broadcast signal receiver having the automatic scanning function, it scans sixteen signal receiving directions with respect to each channel, and sets a direction at which the digital TV broadcast signal can be received in the most suitable condition as an optimum signal receiving direction of each channel.
In such a conventional digital TV broadcast signal receiver, signal receiving conditions of each receivable channel are confirmed in all signal receiving directions of the multi-directional antenna, and the optimum signal receiving direction of each receivable channel is decided, so that it needs a long term for deciding the optimum signal receiving directions of all the receivable channel.
With respect to an apparatus for controlling a signal receiving direction of a multi-directional antenna, for example, Japanese Laid-Open Patent Publication No. 2000-68877 shows an apparatus for controlling a signal receiving direction of an antenna to an optimum signal receiving direction automatically to one of a plurality of broadcast satellites based on information of location of the antenna and information of stationary orbits of the broadcast satellites. Such a conventional signal receiver automatically controls the signal receiving direction of the antenna to a stationary orbit location of the broadcasting satellite, so that satellite broadcast signal can be received corresponding to a channel chosen by the user without bothering a hand of the user. If such a conventional digital TV broadcast signal receiver is used for receiving ground wave digital TV broadcast signal, a signal receiving direction of the antenna to a TV broadcast signal transmission tower (hereinafter, abbreviated as TV tower) will be varied corresponding to a location of the antenna. Furthermore, a ground wave TV broadcast signal is easily affected by multi-path due to megastructure. Thus, it is impossible to shorted a time necessary for deciding an optimum signal receiving direction of each receivable channel.
In addition, for example, Japanese Laid-Open Patent Publication No. 2000-68877 shows an apparatus automatically presetting frequency of receivable channels corresponding to location of the apparatus utilizing information with respect to location of the apparatus. According to utilizing the information of location of the apparatus, optimum signal receiving condition can automatically be set. Such a conventional apparatus, however, has no function for adjusting a direction of an antenna.